Re: [Exim] DNS "query failed" and "timeout" messages

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Author: Phil
Date:  
To: exim-users
Subject: Re: [Exim] DNS "query failed" and "timeout" messages
Hello,

My name is Philippe.

I had been getting DNS timeouts and query failed messages on the machine
running Exim.

It looks like what was happening was this: Exim would be asked to deliver a
message. Exim would contact the DNS servers (external to the network) to
first resolve the domain name of the e-mail it was asked to deliver. The
DNS servers would resolve the domain name and send packets back- the problem
was that our firewall, being misconfigured, interfered with these UDP
packets, and would drop many of them and would not allow them to re-enter
our network and get to Exim.

So Exim was doing just fine all along!! The blame can be laid on the so
called network experts who misconfigured our firewall, which prevented Exim
from doing its DNS communication properly.

Thank you all for your help, especially you Philip Hazel, J2 and Odhiambo
Washington. I greatly appreciate the time, advice and information you gave.

Greetings from New York City, and have a nice weekend everyone.

Phil





------ Forwarded Message
From: Phil <phil@???>
Date: Fri, 15 Feb 2002 18:11:29 -0500
To: <exim-users@???>
Subject: DNS "query failed" and "timeout" messages

Greetings,

The company I work for has recently had the Exim e-mail server installed for
the use of this office, and it's working very well.

I have one question- I'm hoping someone can answer it- I need very much and
as soon as possible to allay the fears that something's wrong with our Exim
server.

We have Exim installed in Mac OSX. In the console logs, we're getting
messages indicating DNS server "timeouts" and "query failed," but we're
seeing this on a constant basis. What worries us is that we're confident
that the actual DNS servers are working properly. These DNS servers
(198.6.1.2, 198.6.1.3, 198.6.1.4, 198.6.1.5) are external to our network and
they are run by a huge company called MCI/WorldCom/UUNET.

Let's say there's an e-mail on the queue whose host can't be resolved by the
DNS servers. Would such an e-mail remain on the queue, so that Exim
continues again and again for days on end with all DNS servers available, to
try to resolve the e-mail's domain name?

If I was told that one e-mail with an un-resolvable domain name could
produce many many many DNS "query failed" and "timeout" messages in the Exim
logs, then I'd feel more comfortable. At the moment though, seeing all
those "query failed" and "timeout" messages, it feels like there's something
very wrong with something.

Can you please help me interpret these logs and let me know if they seem to
indicate a serious problem, and what I should do to troubleshoot or fix it?

Thank you very much for your help, I appreciate it. I hope it's good news
that you have to share!

Philippe Pakter
phil@???

from the console log...

Mac OS X Version 10.1.1 (Build 5M28)
Feb 13 10:17:40 localhost last message repeated 7 times

Feb 13 10:21:40 localhost lookupd[201]: Caught SIGHUP - reset

Feb 13 10:22:09 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

Feb 13 10:22:17 localhost last message repeated 3 times

Feb 13 10:22:17 localhost lookupd[201]: DNSAgent: dns_fqdn_query_server -
query failed for 198.6.1.4

Feb 13 10:22:33 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:35 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:38 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

Feb 13 10:22:50 localhost last message repeated 2 times

Feb 13 10:22:53 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:57 localhost last message repeated 2 times

Feb 13 10:22:57 localhost lookupd[201]: DNSAgent: dns_fqdn_query_server -
query failed for 198.6.1.5

Feb 13 10:23:11 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

etc. etc. etc.

Is this normal or the sign of a problem?

------ End of Forwarded Message